Apparatus for making polymers

ABSTRACT

The invention relates to a device for producing polymers, preferably for processing and polycondensation of polyester, having a substantially cylindrical reactor ( 1 ), which has an inlet opening ( 2 ) on one side and an exit opening ( 4 ) on the other side and an outlet ( 20 ) for discharging gases. According to the invention, said device is developed such that the device has a compact design, and such that the device allows the use of higher-viscosity initial substances, even when generating smaller volumes, which is optimally adjustable in respect of the process conditions thereof and which represents a variable, cost-effective solution. According to the invention, the reactor ( 1 ) has a continuous, central shaft ( 6 ), on which agitating elements or agitating elements and conveying elements are arranged, the inlet opening ( 2 ) is connected to an entry extruder ( 3 ), the shaft ( 6 ) of the reactor and the shaft ( 6 ) of the entry extruder ( 3 ) form a common shaft ( 6 ), and a drive ( 7 ) for the common shaft ( 6 ) is allocated to the entry extruder ( 3 ).

The invention relates to an apparatus for making polymers, preferably for processing and polycondensing polyesters with a reactor that on one side has an intake port and on the other side an outlet port as well as a vent for discharge of gases.

Polymers, particularly polyesters, are produced on a large scale by means of reactors in accordance with DE 695 20 087 [U.S. Pat. No. 5,599,507] or DE OS 19 59 139 [U.S. Pat. No. 3,630,688]. Reactors of that kind are usually charged with low-viscosity to medium-viscosity starting substances with viscosities up to 10 Pas. Cages having stirring elements are arranged in these known reactors. According to DE OS 19 59 139 the reactor additionally has two central shafts that carry the rotary cages.

If polymers or polyesters are to be produced in smaller quantities of, for example, only up to 2,000 kg/h and the starting substances in specific circumstances are also already of higher viscosity, for example with viscosities of approximately 100 Pas or even above that, then these reactors cannot be simply reduced to whatever size in order to still obtain polyesters of high quality. Added to that is the fact that high-power motors and large amounts of energy are needed for drive of the cages.

DE 198 11 280 [U.S. Pat. No. 6,162,837] in fact discloses a apparatus for recovery of linear polyester, in which high-viscosity starting materials can be used, but this apparatus, too, is complicated and has a space-consuming and energy-consuming construction.

U.S. Pat. No. 8,796,401 discloses a reactor that has stirring elements and conveying elements. However, this reactor has neither a vent for discharge of gases nor an intake extruder that is connected with the reactor by a common shaft and common drive. This reactor also serves for large-scale production of high-viscosity polymer materials.

DD 57 700 AS discloses a method for producing polymerization and polycondensation products in which reactors of complicated construction are used. Apart from a charging chamber, a number of reaction chambers is provided here that makes the plant costly and that is not suitable for use for producing smaller amounts of polymers or polyesters.

In addition, U.S. 2011/0105716 A1 discloses a serial arrangement of extruders and reactors that operate separately from one another and that are very complicated and costly. Use for production of smaller amounts of polymers or polyesters is not economically possible with plant of that kind.

DE 103 22 830 [U.S. Pat. No. 7,297,535] discloses a reactor for continuous polymerization of vinylmonomers as well as vinylpolymers. This reactor is constructed as a planetary roller extruder and manages entirely without an intake extruder.

If polymers, preferably polyesters, are to be produced in smaller quantities, the extruder for recovery of plastics material melts according to EP 1 434 680 [U.S. Pat. No. 7,513,677] has already proved satisfactory. Here, an intake extruder and a discharge extruder with a multi-worm extruder component are combined. Polycondensation or polymerization takes place in the multi-worm extruder component. However, the multi-worm extruder component still cannot be set in optimum manner particularly with respect to the processing conditions for polycondensation or polymerization that arise.

The invention has the object of indicating a compact apparatus for making polymers, particularly for polycondensation of polyester, which even in the case of production of smaller amounts allows use of high-viscosity starting substances and is capable of optimum setting in the processing conditions thereof and represents a variable, economic solution.

For fulfilment of this object it is proposed that the reactor has a continuous shaft on which stirring elements or stirring elements and conveying elements are arranged, that the intake port is connected with an intake extruder, that the shaft of the reactor and the shaft of the intake extruder form a common shaft and that a drive for the common shaft is associated with the inlet extruder.

A more compact construction is possible through the connection of the inlet extruder with the reactor. Only one motor is needed that drives both the extruder unit and the reactor unit.

Due to the fact that not only stirring elements, but also stirring and/or conveying elements are provided in the reactor, the polycondensation or polymerization can be better influenced than in a multi-worm extruder component.

A further drive motor can be saved if the outlet port is connected with a discharge extruder and if the shaft of the reactor and the shaft of the discharge extruder form a common shaft. However, there is also the possibility of coupling the outlet port of the reactor with a pump.

It is of advantage if the shaft of the reactor has external teeth and/or a key and if the external teeth and/or the key serves or serve for entraining the stirring elements or the stirring elements and conveying elements arranged on the shaft.

Through the provision of external teeth on the shaft of the reactor it is possible for stirring elements or stirring elements and conveying elements to be seated on a ring with a corresponding internal toothing and to be pushed onto the shaft of the reactor in respectively different sequences depending on requirements, so that the polycondensation or polymerization can be influenced in even more optimum manner.

In that case it is worthy of note that the stirring elements or the stirring elements and conveying elements can be plugged onto the shaft to be exchangeable, so that in the case of changing requirements or in the case or repair a rapid exchange of the relevant elements is possible.

Moreover, it is significant that at least one ring gear meshing with at least one planet wheel is arranged at the inner wall of the reactor, that stirring elements or stirring elements and conveying elements are arranged on the shaft or at least one axle of the planet wheel, and that the at least one planet wheel is mounted in at least one entrainment element arranged on the shaft and/or meshes with at least one sun wheel that is on the shaft of a planetary transmission.

The use of planet wheels with consequently off-center stirring elements or stirring elements and conveying elements may further increase the possibilities of influencing the processing of synthetic material in the reactor.

It is recommended for the ring gears to be fixable to the inner wall of the reactor at freely selectable axial positions. A ring gear opposite a sun wheel can thus be arranged at any desired position.

It is advantageous if disks are provided as stirring elements and if at least one stripper positionable at the reactor wall is associated with the disks.

These strippers can—like, for example, the ring gears—be positioned and fixed to the inner wall of the reactor at a desired position.

Exemplarily, the disk can be arranged at an inclination with respect to the shaft and/or can be corrugated and/or have surface-increasing elements such as nubs

Through these measures it is possible, for example, to achieve even better and more sensitive influencing of the dwell time of the melt in the reactor, the layer thickness of the melt of the reactor, the temperature of the melt in the reactor, etc.

It has proved satisfactory to provide paddle-shaped elements as stirring and/or conveying elements, in which case forward conveying or rearward conveying, but also merely stirring, can be produced by selectable inclined setting of the paddle blades relative to paddle post and/or shaft.

It is recommended to provide helical elements as conveying elements. Thus, for example, a helical element of this kind in the form of a worm section can be arranged at the outlet port and convey the melt out of the reactor.

A particular preference results if the stirring elements consist at least partly of wire mesh and/or perforated plates and/or support plates.

The polycondensation or polymerization can thus be influenced even more individually.

Exemplarily, the reactor is formed to be cylindrical or partly cylindrical and partly conical or, however, conical.

In that case, the reactor not only can taper conically toward its outlet port, but also can initially have a constant diameter increase over its length so that with an otherwise horizontal axis of the reactor the shearing force itself effects transport of the melt toward the outlet port.

If the reactor is capable of inclined setting by means of an inclination setting device from its arrangement with a horizontally disposed axis to an arrangement with at most a perpendicular axis and if every intermediate position of the inclined setting is presettable, preferably variably settable, the user of the reactor is afforded a further possibility of influencing the dwell time of the melt in the reactor.

If an upstream degasifier is associated with the inlet extruder, optionally even plastics material melts with higher viscosity can be fed to the reactor.

The invention is explained in more detail in a drawing. In that case the FIGURE shows a possible example of the construction of a reactor 1, at the intake port 2 of which an intake extruder 3 and at the outlet port 4 of which a discharge extruder 5 are flanged. Intake extruder 3, reactor 1 and discharge extruder 5 have a common shaft 6 rotationally driven by a motor 7.

Paddles 8 serving for stirring the melt deriving from the intake extruder 3 are arranged on an upstream end of the shaft 6 in the reactor 1. Two sun wheels 9 are arranged on the shaft 6 downstream of the paddles 8 in a flow direction of the melt. Ring gears 11 are mounted on the inner wall 10 of the reactor 1 opposite the sun wheels 9. Planet wheels 12 are mounted between the ring gears 11 and the sun wheels 9. Paddles 14 mounted on shafts 13 of the planet wheels 12, depending on the angle of their paddle blades 15, serve for to stir the melt, advance it downstream, or pull it back upstream.

Downstream of the sun wheels 9 on the shaft 6 are disks 17 that can have, like the paddle blades 15, holes, slots or wire mesh (not illustrated).

The disks 17 in the region of the outer circumference thereof are surrounded by strippers 18 fastened to the inner wall 10 of the reactor 1. A helical element 19 serving for conveying the melt from the outlet port in the discharge extruder is provided at the end of the reactor. The reactor 1 is conically formed in the region of the outlet port so that the envelope curve of the helical element, which is basically of worm-shaped construction, is similarly conical.

The extruder has a vent 20 serving for discharge of gases. In that case, the pressure, which is optimal for polycondensation or polymerisation, in the reactor 1 can be set by a preferably regulatable vacuum pump (not illustrated).

Feeders, which are known per se, but not illustrated, for the reactor and/or the extruders are provided that can supply supplements, additives or chemically active substances to the starting material or the melt so as to be able to influence the molecular chains of the polymer in suitable manner. In particular, devices for measuring the viscosity as well as devices for controlling or regulating the addition of the supplements, etc., can also be provided in dependence on the results of the viscosity measurement. Devices, which are known as such and which similarly are not illustrated, for comminuting, homogenizing, compacting the charge material are upstream of the intake extruder and at the same time exert the necessary force for charging. Devices for melt filtration and/or for direct further processing of the polymers can obviously also be connected downstream of the plant.

REFERENCE NUMERAL LIST

1 reactor

2 intake port

3 intake extruder

4 outlet port

5 discharge extruder

6 shaft

7 motor

8 paddle

9 star wheel

10 inner walling

11 ring gear

12 planet wheel

13 shaft

14 paddle

15 blade

16 melt

17 disk

18 stripper

19 helical element

20 vent 

1. An apparatus for processing and polycondensing polyesters, the apparatus comprising: a reactor having on one side an intake port and on the other side an outlet port as well as a vent for the discharge of gases; a continuous central shaft; stirring elements and conveying to elements carried on the continuous central shaft in the reactor; an intake extruder connected to the intake port and surrounding the continuous central shaft upstream of the intake port; and a drive for the continuous central shaft and on the intake extruder.
 2. The apparatus according to claim 1, further comprising: a discharge extruded connected to the outlet port and surrounding the continuous central shaft of the reactor and of the intake extruder downstream of the reactor.
 3. The apparatus according to claim 1, further comprising: a pump connected to the outlet port of the reactor is connected with a pump.
 4. The apparatus according to claim 1, wherein the continuous central shaft has in the reactor external teeth or a key that rotationally drive the stirring elements and conveying elements on the shaft.
 5. The apparatus according to claim 1, wherein the stirring elements or conveying elements can be pushed onto the shaft to be exchangeable.
 6. The apparatus according to claim 1, further comprising: at least one ring gear that meshes with at least one planet wheel fixed on an inner wall of the reactor, the stirring elements or conveying elements being on axle of the planet wheel and that the at least one planet wheel is mounted in at least one of the entrainment elements on the shaft or meshes with at least one sun wheel that is on the shaft of a planetary transmission.
 7. The apparatus according to claim 6, wherein the ring gears can be arranged at and fixed to the inner wall of the reactor at freely selectable axial positions.
 8. The apparatus according to claim 1, further comprising: at least one disk forming a one of the stirring elements and at least one stripper positioned at the inner wall of the reactor and cooperating with the disk.
 9. The apparatus according to claim 8, wherein the at least one disk is oriented at an inclination relative to the shaft and/or is corrugated and/or has surface-increasing elements.
 10. The apparatus according to claim 1, further comprising: paddle-shaped elements serving as the stirring or conveying elements such that forward or rearward conveying, or merely stirring, can be produced by selectable inclined setting of the paddle blades relative to respective paddle posts or shafts.
 11. The apparatus according to claim 1, wherein helical elements are provided as conveying elements.
 12. The apparatus according to claim 1, wherein the stirring elements partly consist of wire mesh or perforated plates or slotted plates.
 13. The apparatus according to claim 1, wherein the reactor is formed to be cylindrical or partly cylindrical and partly conical or conical.
 14. The apparatus according to claim 1, wherein the reactor is obliquely settable by means of an inclination setting device from an arrangement with a horizontally disposed axis to an arrangement at most a perpendicular axis and wherein every intermediate position of the inclined setting is presettable, preferably variably settable.
 15. The apparatus according to claim 1, further comprising: an upstream degasifier associated with the intake extruder.
 16. An extruder assembly comprising: a common central shaft extending along a conveying direction; a reactor housing surrounding a portion of the shaft; stirring and conveying elements operatively connected to the shaft and in the reactor housing; an intake extruder surrounding the shaft upstream of the reactor housing; and a drive at the intake extruder for rotating the shaft and thereby extruding a melt from the intake extruder into an upstream end of the housing and moving the stirring and conveying element to mix and move the melt from the upstream end of the reactor housing in a conveying direction to and out of a downstream end of the reactor housing. 